taeguleon

I know, I know...same old question. No heat. I get a really small air of heat in the upper vent only position, but cold air in the other positions, defrost. This is what I have done so far:
1. Replaced Radiator (Old one was probably good because still have problem)
2. Replaced Water Pump (Old one probably good because still same problem.
3. Replaced radiator cap.
4. Flushed system with Preston Clean and flush, twice, using backflush kit.
5. There are no leaks, idled for 3 hours and drove around for 1 hour. Full radiator.
6. No "sweet smell" or steamy winshield like bad heater core.
7. Tried the OEM 195 degree thermostat and 180 degree, no difference.
8. Did a block test with the "blue liquid" and no color change. No indication of engine fumes in oil or water. Both clean.
9. The intake and outake heater core hoses are hot when engine reached operating temperature.
10. Engine did overheat intermittently but since I did the flush it hasn't. But that doesn't mean it won't.

I am relatively new at working on this Jeep. All the work I learned from YouTube and friends. There may be something out there I am not aware of. Any suggestions would be greatly appreciated. Thanks!

William

tech

Did you do a flush though the heater core ? because if you flush the engine and radiator it can push stuff to the heater .

taeguleon

Thanks for replying! I disconnected both in and out heater core lines and gently flushed the heater core with a garden hose both out through in hose and visa versa. Water flowed normally. Put everything back together and used Prestone flush kit to flush the complete system. I had already done this once before flushing the heater core. The heater core doesn't seem blocked because the"in" hose and "exit" hose are both hot and operating temperature so it looks like the water is flowing through the heater core. When the vent is on upper vent only, it seems to have just a bit of heat after a long idling time. If I put it on defrost only, cold air. Is there a vacuum line possible problem?

taeguleon

BTW, I removed the thermostat and put a new gasket on the thermastat housing before flushing. No leaks. After flushing I installed a new 195 degree thermostat. I believe that is the OEM one.

boxburn

When you move the selector from hot to cold, can you hear the flap moving inside the HVAC unit? Does it feel stiff, free or as you'd expect it to feel changing temperature?

taeguleon

Hey. The fan speeds work normal. When I switch from upper vents, defrost, combinations like defrost floor, etc. I can hear the movement easily. But if I switch from cool air to hot air, I can't hear anything. Am I suppose to? You think it may be a switch problem? BTW, thanks for helping!

William

tech

If you move the switch fast to the end you should hear the temp door hit the close cold or hot , I think the cable hooks up to the bottom of the heater box on the passenger side .

Roler

Google "blend door cable" and it will show you a few cherokee forum threads on this...
On a rhd it's below the glovebox passenger side.

boxburn

Yep, as the others have said you want to be looking at the cable for the blend door. I have no experience with it myself but hope this helps.

Roler

Yep cable end coming off the little stud what happened in mine. I see now it apparently should have a push nut on it 😆